Process of drying hides, skins, and leather



Aug. 16, 1949. WAGNER 2,479,440

PROCESS OF DRYING HIDES, SKINS, AND LEATHER Filed June 26 1947 Fig-l- Inventor: Edward Awagner, 6114; C24

His Attorney.

)atentecl Aug. 16, 1949 UNITED. STATES PATENT OFFICE PROCESS OF DRYI NG HIDES, SKINS,

. AND LEATHER Edward A. Wagner, Pittsfield, Mass. Application June 26, 1947, Serial No. 757,162

Thepresent invention relates to the art of dryng hides, skins and leather. It is generally con- :er'ned with the complete drying operations emloyed during the processing of hides in the nanufacture of leather. While not limited there- ;o, the invention will be particularly described vithreference to thecomplete drying step which .ollows... the fatliquoring of the tanned hide and )y which the. goodsisprepared for finishing op- :rations.

In certain stages during theprocessing of hides, t isdesirable to dry the processed or partially )rocessed material in such amanner that the vater is completely removed from the hide under uch conditions. that the goods will dry flat or mouth and shrinkage will be held to a minimum. For example, in the drying of the tanned goods vhich have been. subjected to a fatliquoring reatment the wet material is drained and subse- Luently dried under controlled temperature and iumidity conditions. At the present time three rincipal methods are employed for stretching the vet goods; In one method the wet material is tretched smoothly over a flat board and attached hereto by tacks driven along the edge of the hide. .hese boards are then stacked vertically and subected to circulating conditioned air. In the econd method, known as the toggle method, the ret hides or skins. are. stretched over perforated aetal frames. and attached thereto by means of. metal clamps. In the third method, known as he pasting method, which has in some cases suplanted both thetoggle and tack methods, the wet ides are. stretched over and pasted onto pasting oards of glass or stainless steel after which the cards with the hides attached are subjected to rying under. controlled temperature and humid- 3! conditions.

A moistureis removed during the drying procsses, employing tacks or toggles, the stretched ide. or leather tends to shrink and pull against lesecuring means. Because of the fact that the rather can shrink to a greater extent between me points at which it is fixedly secured to the ipport, the edge portions of the hides, skins or :atherare unevenly stressed and strained and :equently torn at or adjacent the points at which my are secured to the, support. Asa result the nevenly stressed or punctured edges of the dried roduct must be trimmed off and discarded or )ld as low quality leather.

In the. case of thepasting method, it is necestry to remove the paste from leather and frame fter drying. This involves washing of the frame 1d leather or in some cases sanding of the surlce of. the leather to obtain a thorough removal 5 3.11 of the v paste and adhesive used.

One. object of thepresent invention is to prode a new and improved method of drying wet ides, the term wet hides as used herein and in 1 Claim. (Cl. 69-21) the appended claim being intended to cover both raw and dressed wet hides and skins i. e., the Wet; skins or hides in any stage during the conversion, thereof to leather as well as the drying of the leather, product following any after-treatment which comprises the wetting or'soaking, of the goods with liquid or water-containing compositions.

Another object of the invention is to providea new and improved method of dryingwet-hides, skins and leather with minimum damage of the edge portions of hide.

Additional objects will become apparent from the following description of the invention taken in connection with the accompanying drawing in which i Fig. 1 shows one type of arrangement for drying wet hides in accordance with the present in- Vention;

Fig. 2 is an enlarged view of aportionof Fig. 1; and

Fig. 3 is an enlarged sectional view taken along the lines 3-4 of Fig. 2.

In accordance with the present invention there is provided a combination of the support and holding means for use in drying wet hidesv comprising a supporting member having a surface of, a readily magnetizablematerial, such for example as rolled steel and holding means comprising, a plurality of permanent magnets adapted to hold the wet hide or skin onto the supportingmeans with sufiicient force that, during. drying, the hide: will be permitted to dry in a uniform manner. If desired, a protective coating, such as a. vitreous. enamel or suitable metal, plating, maybe applied: to the hide supporting means or to the magnets: or to both to prevent rust. i

In the modification ofthe invention shown in. the accompanying drawings, a support for the hldeis indicated in Fig. 1 by thenumeral I, this. support comprising a sheet of stainless steel of a size sufiicientto accommodate the cow. hide 2. The wet hideis placedron the sheetof magnetizable material I and is smoothed: out, employing the usual technique, after which a plurality of permanent magnets 3. are arrangedalong' the edge or in other portions of the hide or skin. where they are strongly held by magnetic attraction.

If desired, additional magnets may be placed at.

3 less easily dislodged during handling of vertically positioned boards when lying flat than when positioned perpendicular to the board with their pole faces in full contact with the surface of the goods.

In combination with the support, the magnets provide a uniform tensioning means for the hide. The magnets are preferably of such a strength that during the drying process they will prevent undesirable wrinkling or warping shrinkage. However, by Varying the strength of magnets used, shrinkage may be controlled to any desired degree.

The changes taking place during the drying process when the hide is secured to a magnetizablesheet material by means of a plurality of magnets of a strength to permit limited shrinkage is illustrated in Fig. 2, which is an enlarged view of the upper right corner of the arrangement shown in Fig. 1. In Fig. 2, the edge of the wet hide as originally smoothed out on the board is represented by dotted lines. The magnets 3 used to secure the hide may originally be arranged for example in the dotted line positions. As shrinkage takes place during the drying of the hide, there is a constant pull on each of the magnets directed primarily towards the center of the hide and those portions of the hide which do not underlie a magnet may tend to bow inwardly. By employing magnets so selected as to permit some shrinkage of the hide at all points including those areas in line with the magnets, it is possible to control the variations in the stresses or strains set up along the edge of the hide. If desired, the magnets may be strong enough to exert a clamping-efiect sufficient to provide uniform tensioning and to hold the hide in its original wet position, the stresses and strains caused by shrinkage of the clamped hide during drying are avoided. Generally, the magnets employed should be of sufficient number and strength that the amount of movement thereof during drying is roughly that corresponding to a shrinkage of the hide averaging from -5 percent, preferably from 0-3 percent. When the magnets are so selected and arranged as to permit some shrinkage the edge of the hide and the magnets may assume the full line positions shown in Fig. 2 after the drying step has been completed with the movement thereof during drying being generally towards the center of the hide, it being understood that the magnets and the portions of the hide underlying the faces thereof move together relative to the base plate I. It will be obvious that the total movement, if any, of a particular magnet will depend on the forces set up in the adjacent portions of the hide during drying. When these forces exceed the holding power of the magnet involved, the magnet will give and move allowing shrinkage of the hide until the forces are again less than the holding power of the magnet. By using magnets all of substantially the same strength, the hide will on the whole be subjected to a uniform tensioning during the entire drying process. When the magnets are of a strength permitting shrinkage, the magnets overlying or in line with those parts of the hide subjected to the greatest degree of shrinkage stress will of course move the greatest distance usually towards the center of the hide, during the drying process.

; By the use of magnets in place of tacks or clamps there is obtained a dried hide or leather which is not only free of the perforations resulting from the use of tacks, but which is also more free of the strained or unevenly strained conditions along the edge portions. As a result, little, if any, of the edges of the hide need be trimmed away and discarded as scrap or low value product. By the use of magnets instead of paste as a means A of securing the leather to the drying surface, subsequent washing of the boards and the dried goods to remove the paste is eliminated.

The magnets may be composed of any suitable material having high coercive force and a great stability of magnetic moment. Suitable magnets are those composed of any of the permanent magnet alloys of iron, nickel, aluminum disclosed in Howe Patent 2,192,744. The magnets may also be of any suitable form, as for example, in the form of bars, disks, or U-shaped. A U-shaped magnet such as that shown in the'drawing is particularly useful in that it may be more easily grasped both for the purpose of placing the magnet on the wet hide and for the purpose of removing it from the dry hide. The base I which serves as a keeper or armature for the magnets should preferably be provided with a smooth surface so that the dried hide will have a smooth finish.

The present invention lends itself particularly to use in connection with any of the modern leather drying equipment employing drying boards adapted to be passed through a drying oven. Employing a board of suitable magnetizable material and having a smooth surface, the Wet hide is applied to the surface of. the board, smoothed out along one edge and secured to the board by means of a row of magnets placed along this edge. Thereafter the unsecured portion of the hide is worked or smoothed to stretch the hide and cause it to lie flat and smooth against the surface of the board, the remaining magnets along the outer edge of the hide as well as additional magnets spaced over the area thereof being applied in order as the pockets and wrinkles are worked out of the hide during the smoothing and stretching operations. At least some of the magnets shown in Fig. 1 other than those arranged along the edges of the hide are preferably placed over the thicker and heavier portions of the hide.

While the invention has been described and illustrated in its application to the drying of a wet cow hide, it obviously is not limited thereto but can be used, for example, in the drying of the hide or skin of any animal or reptile or in the drying of selected portions or splits of such hides and skins during the processing thereof in the manufacture of leather or leather-like products.

What I claim as new and desire to secure by Letters Patent of the United States is:

The process of drying hides which comprises placing the wet hide on a magnetizable sheet member, arranging a plurality of permanent magnets along the edges of said hide and in the central portions of said hide for securing said hide to said member, said magnets being of sufficient strength and number as to permit a shrinkage of the hide during drying of from 0-5 percent.

EDWARD A. WAGNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 1,659,957 Millican Feb. 21, 1928 2,177,905 McKeehan Oct. 31, 1939 

